There are several possibilities. First, rule out the obvious stuff:
Watch the electric eye sensors as the door opens and closes - confirm that the sensors remain aligned (the led lights on both remain lit during garage door travel, typically yellow on one, and green on the other); if there is a loose wire or sensor, or if there is excessive vibration or misalignment, the beam may be temporarily broken, causing the door to return to go back up
Confirm that the rails are aligned and straight, the bolts holding them are tight, the wheels on the door sections are tracking smoothly along the rails when the door opens and closes, and the rails are adequately greased to prevent excessive friction or binding during travel; also, ensure there are no other potential obstructions in the way of the garage door mechanism
If you have springs along the upper rail sections (i.e., not a torsion spring set-up), ensure that the tension in the garage door springs on either side is even, and there is similar sag side to side when the door is open; as you observe from the inside, the door should lower evenly (side to side, and in a smooth motion) if the springs are evenly worn, and the spring tension is similar side to side
Confirm that the chain/cable tension on the garage door opener itself is set correctly (there is a certain amount of "sag" expected - check your owners manual for tolerances and how to adjust)
Finally, ensure the door return force limit isn't set too low (without standing directly under the door or otherwise causing injury, of course)
If all of the above checks out (sensors, rails, wheels, springs, all OK, door goes up and door evenly and smoothly, etc.), increasing the downward force slightly may resolve the issue.
In my experience, problems are often sensor-related or random obstructions (like the corner of a box or trash can getting the way of a garage door bracket). If the springs are worn or the tension is too low on one side, the door may close unevenly, causing the wheels to bind up in the rails or strike an obstruction in the rails (like a joint or bolt head).